Windows 7 and Windows Server 2008 R2 have many features geared toward reducing power consumption. In order to achieve greater power savings by processors, they must be able to idle more often and, when idle, stay idle for long periods of time. The following three new features work together to accomplish these goals: Core Parking, Intelligent Timer Tick and Timer Coalescing. Core parking’s dynamically selects a set of processors that should stay idle and not run any threads based on the current power policy and their recent utilization. The scheduler’ll attempt to honor this selection when it decides on which processors to run threads, allowing the parked cores to enter deep idle states where they consume very little power. Intelligent Timer Tick: In Windows 7, the platform timer interrupt no longer automatically wakes application processors, but rather the system timer propagates interrupts onto application processors that are not idle. Cover Timer Coalescing: Timer coalescing is the ability for the Windows kernel to group multiple software timers from different applications and device drivers, and expire them all at the same time.
Full Article: Performance team